#include<iostream>#include<stdio.h>#include<string.h>#include<cmath>#include<map>#include<algorithm>#define ll long longusing namespace std; struct node{ int w[25],num;}ans; char s[25][105]; int n;map<int,node> mymap;void dfs1(int i,int x,node h){ int l,j; if (mymap.find(x)==mymap.end()) mymap[x]=h; if (mymap[x].num<h.num) mymap[x]=h; if (i>n/2) return; dfs1(i+1,x,h); l=strlen(s[i]); for (j=0;j<l;j++) x^=1<<(int)(s[i][j]-'A'); h.w[++h.num]=i; dfs1(i+1,x,h); return;}void dfs2(int i,int x,node h){ int l,j; if (mymap.find(x)!=mymap.end() && mymap[x].num+h.num>ans.num) { ans=mymap[x]; for (j=1;j<=h.num;j++) ans.w[++ans.num]=h.w[j]; } if (i>n) return; dfs2(i+1,x,h); l=strlen(s[i]); for (j=0;j<l;j++) x^=1<<(int)(s[i][j]-'A'); h.w[++h.num]=i; dfs2(i+1,x,h); return;}int main(){ int i; node h; scanf("%d",&n); for (i=1;i<=n;i++) scanf("%s",s[i]); h.num=0; mymap.clear(); dfs1(1,0,h); ans.num=0; dfs2(n/2+1,0,h); printf("%dn",ans.num); for (i=1;i<=ans.num;i++) printf("%d ",ans.w[i]); return 0;}
